Composition for use in eliminating oil and grease smudges from offset printing mats and plates



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COMPOSITION FOR USE IN ELINIINATING OIL AND GREASE SMUDGES FROM OFFSETPRINT- ING MATS AND PLATES Oliver S. Nichols, Granite City, 111.,assignor of one-half to John H. Schneider, Lake Bluff, lll.

No Drawing. Application November 16, 1951, Serial No. 256,829

2 Claims. c1. 101-4491 This invention relates to a liquid compositionfor use upon planographic printing plates including parchment or likecellulose base and metal planographic plates, and in particular toliquid compositions for the elimination of oil and grease smudges fromsuch plates or mats, and to a method of making the said composition.

Briefly stated, the composition of this invention comprises a mixture ofa water-miscible aliphatic alcohol selected from the group consisting ofisopropyl alcohol, glycerol and glycols with water and an aqueouscolloid dispersion of silicic acid, said mixture being adjusted to a pHin the range of 3-5, and desirably buffered in that range. Theeffectiveness of the composition in removing oil and grease smudges fromoffset mats or plates is developed by the addition of a water-immisciblesolvent, such as a petroleum ether solvent, to the mixture and shakingtogether the two layers thus formed to provide a dispersion of dropletsof the solvent throughout the aqueous layer before applying thecomposition to the smudges on the mat or plate.

Among the objects of this invention is the provision of a novelcomposition for the elimination of oil and grease smudges from offsetprinting mats or planographic plates; the provision of a composition forthe removal of oil and grease smudges from offset printing mats orplanographic plates; the provision of a composition for the removal ofoil and grease smudges from offset printing mats and plates which iscompatible with the repellent solutions employed in preparing the mat orplate for the inking operation and free from any effect upon suchrepellent solutions when employed for their intended purpose; theprovision of a composition for eliminating oil and grease smudges fromoffset printing mats and plates with a minimum of deterioration orweakening of the image or ink lines present on the mat and which are tobe reproduced; the provision of an aqueous composition which, whenagitated with a water-immiscible organic solvent of the petroleum ethertype to disperse the solvent throughout the aqueous phase in the form ofdroplets and applied to offset printing mats and plates, renders oil andgrease smudges present on the mats and plates incapable of attractingink during the planographic printing process; and the provision of amethod for making oil and grease smudge elimination compositions. Otherfeatures will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the ingredients and combinations ofingredients, the proportions thereof, steps and sequence of steps, andfeatures of composition and manipulation, which will be exemplified inthe products and methods hereinafter described, and the scope of theapplication of which will be indicated in the following claims.

In the preparation of planographic printing plates for the printingoperation, etching solutions are applied to the plate to render thenon-printing areas of the plate repellent to greasy or fattyacid-containing planographic printing inks. Similarly, in thepreparation of plates rates Patent 9 2,780,168 Patented Feb. 5, 1957 ormats of parchment or like cellulose base for the offset printingoperation, so-called etching or repellent solutions are applied torender the non-printing areas of the mat repellent to greasy or fattyacid-containing planographic printing inks. In the handling of theseplates or mats before, during or after the operation of applying to theplate or mat the image or impression which is to be copied, oil andgrease smudges are frequently formed on the plates or mats as a resultof contact with the fingers of the operator or others who handle theplate or mat, or as a result of contact with the plate or mat with oilyor greasy surfaces or objects. The smudges thus formed are frequentlytransparent and hence escape the notice of the operator until the mat isplaced on the duplicating machine, inked and impressions are run off. Atthat time, the oil or grease smudges attract ink and print off on theblanket of the machine and thereafter on the impression paper areas ofink corresponding to the areas covered by the oil or grease smudges.These ink smudges resulting from the attraction of ink to the oil orgrease smudges frequently cover large areas of the impression copy andrender the copy illegible and unsightly. The oil or grease smudges arenot effectively removed from the mat by rubbing the mat withconventional etching or repellent solutions and any dimunition in theextent of the oil or grease smudge by this means is accompanied withdamage or weakening of the impression to an extent which renders itimpractical to attempt to remove oil or grease smudges with conventionaletching or repellent solutions in this manner. The presence of oil andgrease smudges on offset printing mats and plates and the lack of anyeffective means or material heretofore for removing or dispersing theseoil or grease smudges has generally handicapped the utility of theoffset printing mat as a medium for producing legible, clean copies.

According to the present invention, generally stated, an effectivecomposition for eliminating oil and grease smudges from offset printingmats and plates substantially without weakening the image on the mat isprovided by mixing a water-miscible aliphatic alcohol selected from thegroup consisting of isopropyl alcohol, glycerol and glycols, with anaqueous colloid dispersion of silicic acid, adjusting the pH of thesolution to a pH within the range of 3-5, for example, by the additionof a small quantity of an acid, and desirably buffering the solution,forexample, by the addition of ammonium dihydrogen phosphate to thesolution. This solution when mixed with a water-immiscible organicsolvent such as mineral spirits having a boiling point range of 300-317"F. and a specific gravity of 0.782 and agitated to disperse thewaterimm'iscible organic solvent as droplets throughout the aqueousportion, provides an effective composition for application to offsetprinting mats, for example, by means of a wad of cotton soaked with thesolution and rubbed on the smudged portions, over the entire surface ofthe mat. Inasmuch as it has been found unnecessary to remove thecomposition from the mat after the rubbing operation, the compositionmay be said to render the smudges ineffective as ink-attracting areas,probably by dispersing the oil or grease smudges in the composition asit is rubbed over the met and preventing the oil or grease thereafterfrom redepositing on the mat or attracting ink. The dispersion ofdroplets of the water-immiscible solvent in the aqueous portion byshaking the two layers together serves to provide sufficient of the twolayer components in conjunction with each other on the surface of themat so that these materials can cooperate to produce the desired result.The droplets tend to coalesce quickly upon standing and it is necessaryto shake the layers together each time before applying the compositionto the cotton wad or other medium for application to. the mat.

The composition composed of the aqueous and non-aqueous layers ma'y'beemployed in the form of a stable emulsion produced with the aid of asuitable emulsifying agent. However, it has not been found necessary toresort to that practice and furthermore it is desirable in the offsetprinting process to avoid emulsions which may tend to emulsi-fy thegreasy or fatty acld base inks and thereby weaken the image on the mator blur the impression on the copy paper.

The composition of this invention may be applied either before or afterthe application of the conventional etching or repellent solutionnormally applied to the mat for rendering the non-printing areasrepellent to grease and fatty acid-containing plano'graphic inks. Theoperator may apply the composition over the entire surface of the matbefore the mat is placed on the duplicating machine or may run off animpression on the duplicating machine to locate smudged areas on therepellentwetted mat through their ink-attracting characteristics and maythen rub the composition over the smudged areas while the mat is inposition on the machine to disperse and sequester the oil and greasesmudges in the applied composition and thereby render the smudges i11-capable of attracting the ink in the subsequent running off of copies orimpressions on the machine. The composition of this invention has beenfound to remove oil and grease smudges on offset printing mats andplates, including those areas of the plate or mat on which lines ortyping are present, without weakening the lines or the typing. Aftertreatment of the plate or mat with the composition, the impressions runoif on the duplicating machine show the lines and typing as clearly asthough the oil and grease smudges had never been present on the plate ormat. it has further been found that any residual ink smudge on theblanket of the duplicating machine after the mat has been treated withthe composition of this invention will run off and become dissipated ina few copies and thereafter be absent from the subsequent copies. it isunnecessary therefore to clean the blanket roll for the purpose ofremoving the ink transfer thereto by oil or grease smudges as long asthe composition of the present invention has been employed on the matfor the purpose of dispersing the oil and grease smudges. It isgenerally the custom in the offset printing trade to allow mats to standfor approximately twelve hours before running them on the duplicatormachine, in order to set or age the ink lines or typing and thereby tominimize any tendency for the lines or typing to wear off rapidly. Thispractice is desirable in connection with the application of thecomposition of the present invention to oil and grease smudges on themats, out is not essential, since the composition may be applied to matswhich have not been aged quite as long as the customary period.

Illustrative of the water-miscible aliphatic secondary alcohol suitablefor the purpose of the present invention is isopropyl alcohol.Illustrative of the water-miscible gly cols for the same purpose areethylene glycol, propylene glycol, triinethylene glycol and diethyleneglycol. Glycerol is the preferred trihydric alcohol. These aliphaticalcohols are miscible with Water in all proportions and hence theconcentrations of the alcohol for the purpose of this invention can bereadily attained. The watermiscible aliphatic alcohol content of thecomposition of the present invention may be varied between the limits of-80 parts by volume of the aqueous solution, and preferably between thelimits of 10-4O parts by volume. A small quantity of a Water-solublealdehyde, for example, 0.l2% by Weight of the aqueous solution, forexample, formaldehyde, acetaldehyde or furfuraldehyde, when added to thesolution, particularly at the higher concentrations of thewater-miscible aliphatic alcohol, serves to prevent the composition fromforming an oil-inwater type of emulsion with fatty or greasylithographic inks and consequent glazing of the ink rolls ofpianographic printing presses or duplicators. In most instances, thealdehyde has not been found necessary.

The pH of the composition in the range of 3-5 may be elfected by theaddition of small quantities of an acid such as phosphoric, axalic,glycolic, glyoxylic, pyruvic acids or the like. It frequently happensthat glycols contain sufficient acid as a result of oxidation onstanding to render their aqueous solutions acidic in the pH range of3-5. In that case, no additional acid need be added. The aqueouscomposition'is desirably buttered in the pH range of 3-5, for example,by the addition of a builering agent which will maintain the pH of theaqueous solution in that range. Mono-ammonium dihydrogen phosphate inthe amount of 2% by weight of the aqueous solution (i. e., prior to theaddition of the Water-immiscible solvent) has been found satisfactoryfor this purpose. Smaller or larger quantities of the buffering agentmay be employed but it is desirable to maintain the concentration ofboth the acid and the bulfering agent at as low a level as possible andstill achieve a stable pH in the range of 3-5. While fatty acids such asacetic andpropionic acids may be employed for the acidifying operation,it is desirable to avoid the use of fatty acids, sincethey tend toweaken the image on the mat and render the image less capable ofattracting ink when the mat is inked for the purpose of. preparingcopies. Strong acids such as phosphoric and sulfuric acid may beemployedin sparing amounts.

The aqueous colloidal silicic acid dispersion component of the aqueouscomposition of this invention is conventionally prepared by passingaqueous sodium ortho silicate solutions through'a bed of cation exchangeresins and then through a bed of anion exchange resins to remove all buta trace of the cations and anions, leaving a colloidal solutionofsilicic acid which may range in silicic acid content from 1-15% ormore byweight, depending upon the concentration of the sodium orthosilicate starting solution. Other methods of preparing the colloidalsolution of silicic acid may be employed. The quantity of aqueouscolloidal silicic acid solution for admixture with the other componentsof the composition of this invention may vary Widely. For example, a 1%colloidal silicic acid solution (20 cc.) when admixed with a solution ofglycerol (35 cc.) in water (45 cc.), which latter solution has beenadjusted in pH to within the range of 3-5 by the addition of 0.5 cc. ofphosphoric acid, and agitated with a petroleum solvent (ll) cc.) havinga boiling point range of 300-317" F. and a specific gravity of 0.782,has been found very eifective in dispersing oil and grease smudges onoffset printing mats. Smaller concentrations of colloidal silicic acidsolution may be employed in the composition of the present in ventionwith diminishing effectiveness. Larger amounts are desirable and theupper limit is fixed by the amount of Water permissible in thecomposition in view of the concentration of the Water-miscible aliphaticalcohol selected.

The Water-immiscible organic solvent employed in the composition of thepresent invention is desirably selected from among those petroleumsolvents known as petroleum ethers, consisting essentially of paratfins,chiefly hexane and heptane', both mixed and straight, which possess asufficiently slow rate of evaporation to permit the droplets of solventto remain in contact with the oil or grease smudge on the matinconjunction with the aqueous portion of the composition long enough todisperse the oil or grease in the composition without evaporatingprematurely with subsequent'redeposition of the oil or grease upon themat. Once the oil or grease has been dispersed in the composition ofthis invention as applied to the mat, there appears to be no tendencyfor the oil or grease thereafter to attract ink in the subsequent inkingoperation. The quantity of water-immiscible solvent employed with theaqueous composition may be relatively small, since it is only necessaryto provide a dispersion of droplets of the solvent throughout theaqueous composition at the time the composition is applied to oil andgrease 15 smudges. For example,.10 ml. of water-immiscible solventaddedto 100 cc. of the aqueous composition has been found to be adequate.More or less than this amount may be employed. Too much of thewaterimmiscible solvent tends to leave a residue of solvent on the matwhich will tend to attract ink and print out as anink smudge on theimpressions. A desirable solvent for the purpose of the presentinvention has been found to be a mineral spirits fraction having aboiling point range of 300-317 F. and a specific gravity of 0.782.Another petroleum ether solvent known to the trade as Stoddards solvent,having a boiling point range of 300- 400 F., has been foundsatisfactory. Other mineral spirits solvents having boiling point rangesof 3l0360 F. and 360-410 R, respectively, and specific gravities of0.7699 and 0.7857, respectively, have been found satisfactory. Otherwater-immiscible solvents having the aforescribed properties as well asthe characteristics described hereinbefore in conjunction with thecomposition of the present invention may be employed. Many of thepetroleum solvents available commercially contain portions of aromaticsolvents. Such petroleum solvents have also been found satisfactory forthe purpose of the present invention when they possess a suitably lowevaporation rate.

The composition containing the water-miscible aliphatic alcohol,colloidal silicic acid solution, water and hydrogen ions may bedispensed commercially in suitable containers such as glass bottles andthe petroleum ether may be added to the container or to a portion of thesolution and shaken therewithjust prior to using 'the composition onoffset printing mats and plates.

.The following examples will serve to illustrate the methodsand productsof the present invention:

Example I Parts by volume Propylene glycol (containing acidic oxidationproducts 40 Water 40 Colloidal silicic acid solution (1% silicic acid byweight, in water) 20 The propylene glycol and water were mixed and thecolloidal silicic acid solution was admixed therewith. The resultingsolution was found to have a pH in the range of 3-5 as a result of theacidic oxidation products present in the propylene glycol. To thesolution was added mineral spirits ml.) having a boiling point range of300-317 F. and a specific gravity of 0.782.

.The two layers were shaken together until the mineral spirits .becamedispersed in the aqueous layer in the form of small'droplets. Thecomposition was then 'applied by means of a piece of cotton 'soaked withthe mixture to a cellulose base offset printing mat (known to the tradeas Colitho) upon which drawings and typing had been executed and oil andgrease smudges had been deposited through handling of the mat by variouspersonnel. The that had previously been wetted with a glycerol-baseetching or repellent solution, inked on a duplicator machine and severalcopies run therefrom. .The oil and grease smudges which were invisibleprior to the inking operation attracted ink and transferred an image ofthe smudges to the copies. The oil and grease smudge eliminatingcomposition of the invention as illustrated hereinabove was then appliedto the wetted mat with moderate rubbing over the areas of the matcorrespondingto theareas of visible ink smudge on the copies. The matwas then inked in the machine and copies were run oif. After a run-offof several copies, the ink smudges ceased to appear on the copies. The

' lines of the drawings and the typing appearing on the copies wereclear and sharp with substantially no evidence of weakening of the imageon the mat through application of the smudge eliminating composition tothe lines and typing on the oifset printing mat. This was evidence ofthe fact that the smudge removing composition did not destroy the linesof the drawing and typing or weaken them was to render them incapable ofattracting ink during the inking operation, or interfere in any mannerwith, the proper functioning of the printing operation.

It was also found that the smudge eliminating composition could beapplied to the mat prior to the wetting of the mat with a repellentsolution with equally good results, rubbing the composition over theentire area of the surface of the mat to insure that any invisible oilor grease smudges present on the mat were eliminated.

Example ll Parts by volume Glycerol 30 Mono-ammonium dihydrogenphosphate (10% by weight, solution in water) l0 Colloidal silicic acidsolution (5% silicic acid by weight, in water) 10 The glycerol wasdissolved in the mono-ammonium dihydrogen phosphatesolution and thecolloidal silicic acid solution was admixed therewith. To the solutionthus formed was added phosphoric acid (0.5 ml., The pH of the solutionwas in the range of 3-5. To the resulting mixture ml.) was added apetroleum ether fraction (10 ml.) having a boiling point range of310-360 F. The resulting composition was shaken to disperse thepetroleum ether layer in the form of fine droplets throughout theaqueous layer and was then applied to an oifset printing mat in themanner described in Example I with good results.

Example III Parts by volume Furfuraldehyde Colloidal silicic acid (5%silicic by Weight, in water)- 20.0

The furfuraldehyde and mono-ammonium dihydrogen phosphate were mixedtogether in the water and the glycerol and colloidal silicic acidsolution were mixed. The two solutions were then thoroughly mixedtogether and the resulting composition was acidified with 0.5 g. ofglycollic acid. The resulting composition was found to have a pH in therange of 3-5. Mineral spirits (10 ml.) having a boiling point range of360-410 F. and a specific gravity of 0.7857 was added to the compositionand the resulting composition was agitated to disperse the mineralspirits in the form of fine droplets throughout the aqueous layer.

The composition as thus prepared as applied to oil and grease smudges onoffset printing mats according to the procedure described in Example Iwith excellent results.

Example IV Parts by volume Formaldehyde (37% in water) (Formalin)Mono-ammonium dihydrogen phosphate (2% by weight, in water) 24.5Glycerol 20.0 Water 35.0

Colloidal silicic acid solution (1% silicic acid by weight, in water)20.0

The formaldehyde and mono-ammonium dihydrogen phosphate solution weremixed and to this solution was Example V Parts by volume Isopropylalcohol 40 Mono-ammonium dihydrogen phosphate (2% by weight, in water)4O Colloidal silicic acid solution (1% silicic acid by weight, in water)20 The isopropyl alcohol and mono-ammonium dihydrogen phosphatesolutionwere mixed and to the resulting solution was added the colloidalsilicic acid solution. The solution was found to have a pH in the rangeof 3-5. The solution (100 ml.) was placed in a bottle until the occasionarose to remove oil and grease smudges from offset printing mats. Atthat time, a petroleum ether fraction (20 ml.) having a boiling point'inthe range of 300-317'F. was added and the twolayers were shaken togetheruntil the petroleum ether fraction became dispersed throughouttheaqueous layer in the form of fine droplets. The resulting dispersionwas then applied by means ofa piece of cotton to the oflset printingmat, rubbing the solution over the areas bearing the oil and greasesmudges. The printing mat was then placed in a duplicator machine andinked in the usual manner. After a run-off of several copies, thesubsequent impressions were found to be entirely free of ink smudgesresulting from the attraction of ink by oil and grease on the mat.

Example V1 Parts by volume Ethylene glycol 1O Ammonium dihydrogenphosphate (2% by weight,

in water) 3O Colloidal silicic acid solution silicic acid by weight, inwater) 60 The ethylene glycol and ammonium dihydrogen phosphate solutionwere mixed and the colloidal-silicic acid solution was added to themixture. Glycolic acid was added to the solution until the pH ofthesolution was in the range of 3-5. To the composition (100 ml.) thusprepared was added a petroleum ether fraction (10 ml.) having a boilingpoint in the range of 310-360 F. The two layers were agitated togetherto disperse the waterimmiscible layer in the aqueous layer in the formof fine droplets. The resulting composition was applied to oil andgrease smudges on cellulose-base oifset printing mats in the mannerdescribed in Example I with good results.

Example VII Parts by volume The components were mixed in the orderpresented hereinabovc and a petroleum ether fraction (10 ml.) hav ing aboiling point in the range of 300-317 F. was added. The two layers wereshaken together to disperse the petroleum ether fraction in the form ofdroplets throughout the aqueous layer and the composition was applied tooffset printing mats in the manner described in Example I with excellentresults.

In view of the above, it will be seen-that the several objects of theinvention are achieved and other advantageous results attained.

As many changes could be made in the above methods and productswithoutdeparting from the scope of the invention, it is intended thatall matter contained in the above description shall be interpreted asillustrative and not in a limitingrsense.

I claim:

1. A composition for rendering oil and grease smudges present onplanographic mats and plates incapable of attracting ink during theplanographic process, comprising as an aqueous phase 10-80 parts byvolume of a watermiscible aliphatic alcohol selected from the groupconsisting of glycerol and glycols, water and 1060 parts by volume of acolloidal solution of silicic acid in water containing 1-15 by weight ofsilicic acid, said aqueous phase containing suflicient hydrogen ions toestablish a pH in the range of 3-5, and as a non-aqueous phase about 10ml. per 100 m1. of solution of a petroleum ether fraction boiling withinthe range of 300-420 F., said petroleum ether fraction adapted to bedispersed throughout said aqueous phase in the form of droplets byagitation of said phases together at the time of application of thecomposition to mats and plates.

2. A method for rendering. oil and grease smudges present onplanographic mats and plates incapable of attracting ink during theplanographic process comprising intimately contacting said smudges witha composition comprising as an aqueous phase 10-80 parts by volume of awater-miscible aliphatic alcohol selected from the group consisting ofglycerol and glycols, water and 10-60 parts by volume of a colloidalsolution containing 1-1S% by weight of silicic acid in water, saidaqueous phase having a pH in the range of 35, and as a non-aqueous phase10 ml. per ml. of solution of a petroleum ether fraction having aboiling point within the range of 300-420 F., said non-aqueous phasebeing dispersed throughout said aqueous phase in the form of droplets asa result of agitation of the two phases together at the time ofapplication of said composition to said mats and plates.

References Cited in the file of this patent UNITED STATES PATENTS1,892,875 Dietz Jan. 3, 1933 1,911,239 Reed et al May 30, 1933 1,922,006Von Hoessle' Aug. 8, 1933 1,977,646 Rowell Oct. 23, 1934 2,016,517Rowell Oct. 8, 1935 2,132,443 Simons Oct; 11', 1938 2,233,573 Ayers Mar.4, 1941 2,297,929 Wise Oct. 6, 1942 2,311,047 Hagelin Feb. 16, 19432,356,773 Marshall Aug. 29, 1944 2,393,875 Van Dusen Jan: 29, 1 9462,433,780 Marshall Dec. 30, 1947 2,515,536 Van Dusen' July 18, 19502,534,588 Frost Dec. 19, 1950 2,561,354 Finno -2 'July 24, 19512,635,056 Powers Apr. 14, 1953 2,681,617 Worthen et al June 2 2, 1954FOREIGN PATENTS 8,544 Great Britain May- 18,- 1916 OTHER REFERENCESConant: The Chemistry of Organic Compounds. Revised ed. 1939, MacMillanCo., N. Y. Only page 277 cited. (Copy available in Division 17.)

Ellis: Printing Inks, 1940. Reinhold Pub. Co., N. Y. Only pages 259 and260 cited. (Copy available in-Div. 17.)

2. A METHOD FOR RENDERING OIL AND GREASE SMUDGES PRESENT ON PLANOGRAPHICMATS AND PLATES INCAPABLE OF ATTRACTING INK DURING THE PLANOGRAPHICPROCESS COMPRISING INTIMATELY CONTACTING SAID SMUDGES WITH A COMPOSITIONCOMPRISING AS AN AQUEOUS PHASE 10-80 PARTS BY VOLUME OF A WATER-MISCIBLEALIPHATIC ALCOHOL SELECTED FROM THE GROUP CONSISTING OF GLYCEROL ANDGLYCOLS, WATER AND 10-60 PARTS BY VOLUME OF A COLLOIDAL SOLUTIONCONTAINING 1-15% BY WEIGHT OF SILICIC ACID IN WATEAR, SAID AQUEOUS PHASEHAVING A PH IN THE RANGE OF 3-5, AND AS A NON-AQUEOUS PHASES 10 ML. PER100 ML. OF SOLUTION OF A PETROLEUM ETHER TRACTION HAVING A BOILING POINTWITHIN THE RANGE OF 300-420* F., SAID NON-AQUEOUS PHASES BEING DISPERSEDTHROUGHOUT SAID AQUEOUS PHASES IN THE FORM OF DROPLETS AS A RESULT OFAGITATION OF THE TWO PHASES TOGETHER AT THE TIME OF APPLICATION OF SAIDCOMPOSITION TO SAID MATS AND PLATES.